Extreme ultraviolet radiation source and droplet catcher thereof

Abstract

An extreme ultraviolet radiation source is provided, including a droplet generator and a droplet catcher. The droplet generator is configured to output a plurality of target droplets along a target droplet path that is parallel to a horizontal direction. The droplet catcher includes an open end substantially aligned with the target droplet path, and an enclosed end that is opposite to the open end. The droplet catcher also includes a pipe wall disposed between the open end the enclosed end. The pipe wall includes a first pipe wall portion having an inner top surface parallel to the horizontal direction and an inner bottom surface inclined relative to the inner top surface. In addition, the droplet catcher includes at least one gutter formed on the inner bottom surface and having a long axis extending along the horizontal direction.

What is claimed is: 
     
       1. An extreme ultraviolet radiation source, comprising:
 a droplet generator configured to output a plurality of target droplets along a target droplet path that is parallel to a horizontal direction; and 
 a droplet catcher, comprising:
 an open end substantially aligned with the target droplet path; 
 an enclosed end being opposite to the open end; 
 a pipe wall disposed between the open end and the enclosed end, wherein the pipe wall includes a first pipe wall portion having an inner top surface parallel to the horizontal direction and an inner bottom surface inclined relative to the inner top surface; and 
 at least one gutter formed on the inner bottom surface and having a long axis extending along the horizontal direction. 
 
 
     
     
       2. The extreme ultraviolet radiation source as claimed in  claim 1 , wherein the inner bottom surface of the first pipe wall portion has a decreasing slope toward the enclosed end. 
     
     
       3. The extreme ultraviolet radiation source as claimed in  claim 1 , wherein an angle is formed between the inner bottom surface of the first pipe wall portion and the horizontal direction, the angle being between about 1 degree and about 30 degrees. 
     
     
       4. The extreme ultraviolet radiation source as claimed in  claim 1 , further comprising a heating element thermally coupled to the first pipe wall portion. 
     
     
       5. The extreme ultraviolet radiation source as claimed in  claim 1 , wherein the first pipe wall portion is adjacent to the open end. 
     
     
       6. The extreme ultraviolet radiation source as claimed in  claim 5 , wherein the pipe wall further includes a second pipe wall portion disposed between the first pipe wall portion and the enclosed end, and the second pipe wall portion is at an angle to the horizontal direction, the angle being between about 1 degree and about 45 degrees. 
     
     
       7. The extreme ultraviolet radiation source as claimed in  claim 6 , wherein the gutter is extending through a second inner bottom surface of the second pipe wall portion, along the horizontal direction, toward the enclosed end. 
     
     
       8. The extreme ultraviolet radiation source as claimed in  claim 7 , further comprising a heating element thermally coupled to the second pipe wall portion. 
     
     
       9. The extreme ultraviolet radiation source as claimed in  claim 1 , wherein the gutter has a U-shaped cross-section. 
     
     
       10. The extreme ultraviolet radiation source as claimed in  claim 1 , wherein the gutter has a V-shaped cross-section. 
     
     
       11. The extreme ultraviolet radiation source as claimed in  claim 1 , wherein a bottom of the gutter includes at least one step. 
     
     
       12. The extreme ultraviolet radiation source as claimed in  claim 1 , further comprising a plurality of gutters formed on the inner bottom surface of the first pipe wall portion and parallel to each other. 
     
     
       13. The extreme ultraviolet radiation source as claimed in  claim 1 , further comprising:
 a laser source configured to generate a laser beam to heat the target droplets to produce extreme ultraviolet light; 
 a collector configured to collect and reflect the extreme ultraviolet light. 
 
     
     
       14. A droplet catcher for an extreme ultraviolet radiation source, comprising:
 an open end allowing a plurality of target droplets to enter the droplet catcher; 
 an enclosed end being opposite to the open end; 
 a pipe wall disposed between the open end and the enclosed end, wherein the pipe wall includes a first pipe wall portion having an inner top surface parallel to a horizontal direction and an inner bottom surface inclined relative to the inner top surface; and 
 at least one gutter formed on the inner bottom surface and having a long axis extending along the horizontal direction. 
 
     
     
       15. The droplet catcher as claimed in  claim 14 , wherein the inner bottom surface of the first pipe wall portion has a decreasing slope toward the enclosed end. 
     
     
       16. The droplet catcher as claimed in  claim 15 , wherein the gutter has a depth lower than the inner bottom surface of the first pipe wall portion. 
     
     
       17. The droplet catcher as claimed in  claim 14 , further comprising a heating element thermally coupled to the first pipe wall portion. 
     
     
       18. The droplet catcher as claimed in  claim 14 , wherein the first pipe wall portion is adjacent to the open end, and an end of the gutter is a distance away from the open end. 
     
     
       19. The droplet catcher as claimed in  claim 18 , wherein the pipe wall further includes a second pipe wall portion disposed between the first pipe wall portion and the enclosed end, and the second pipe wall portion is at an angle to the first pipe wall portion to form a reservoir for capturing the target droplets. 
     
     
       20. A droplet catcher for an extreme ultraviolet radiation source, comprising:
 an open end allowing a plurality of target droplets to enter the droplet catcher; 
 an enclosed end being opposite to the open end; 
 a pipe wall disposed between the open end the enclosed end, wherein the pipe wall includes a first pipe wall portion having an inner top surface and an inner bottom surface parallel to a horizontal direction; 
 at least one gutter formed on the inner bottom surface and having a long axis extending along the horizontal direction, wherein a distance between the inner bottom surface and a bottom of the gutter gradually increases toward the enclosed end; and 
 a heating element thermally coupled to the first pipe wall portion.